Shell and tube evaporator

ABSTRACT

An evaporator for use in a refrigeration system, the evaporator having a shell defining an interior volume enclosing a tube bundle comprising a plurality of elongate tubes, a water inlet in fluid communication with a first end of the of the tube bundle for directing water to the first end of the tube bundle and a water outlet in fluid communication with a second end of the tube bundle for passing water received from the second end of the tube bundle out from the interior volume, includes a plurality of fluid deflectors in fluid communication with a refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout the interior volume. A method of forming an evaporator is further included.

TECHNICAL FIELD

The present invention relates to refrigeration systems. More particularly, the present invention relates to direct expansion evaporators for use in refrigeration systems.

BACKGROUND OF THE INVENTION

Evaporators for use in refrigeration systems are well known. There is a need to improve the efficiency of evaporators and to achieve a cost advantage in the evaporator market.

A problem with existing evaporators is that a refrigerant vapor tends to float in the evaporator while a liquid refrigerant tends to sink to the bottom of the evaporator. Such distribution results in a decreased efficiency of the evaporator. There is a need then to better mix refrigerant in both the liquid and vapor states in order to better distribute the refrigerant throughout the evaporator in the mixed condition. Such enhanced distribution would contribute to an increased efficiency of the evaporator.

SUMMARY OF THE INVENTION

The present invention substantially meets the aforementioned needs of the industry. The present invention provides for a relatively simple means of mixing the liquid and vapor refrigerant for better distribution of the mixed refrigerant throughout the evaporator. The present invention provides for refrigerant deflectors, more preferably vanes, disposed proximate the refrigerant inlet. The vanes are variably angled with respect to a center line of the evaporator in order to direct refrigerant both upward and downward as the refrigerant enters the evaporator.

The aforementioned vanes can be integrated within a generally conical endplate of the evaporator. In order to minimize cost, the vanes may be cast integrally with the endplate. A one piece endplate that incorporates the vanes of the present invention substantially reduces cost of incorporation of the present invention within an evaporator.

The present invention is an evaporator for use in a refrigeration system, the evaporator having a shell defining an interior volume enclosing a tube bundle comprising a plurality of elongate tubes, a water inlet in fluid communication with a first end of the tube bundle for directing water to the first end of the tube bundle, and flow through baffle plates for best heat transfer and a water outlet in fluid communication with a second end of the tube bundle for passing water received from the second end of the tube bundle out from the interior volume, including a plurality of fluid deflectors in fluid communication with a refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout the interior volume. The present invention is further a method of forming an evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an evaporator incorporating the present invention and depicting the tube bundle resident within the evaporator.

FIG. 2 is a perspective view of the tube sheet plate.

FIG. 3 is a perspective view of the exterior of an endplate.

FIG. 4 is a perspective view of the interior of the endplate of FIG. 3, depicting the vanes of the present invention.

FIG. 5 is a side view of the endplate of FIG. 3 cut away to depict the angled disposition of the vanes.

FIG. 6 is a perspective view of an evaporator having two independent refrigerant flow paths flowing inside of the tubes of the tube bundle.

FIG. 7 is an exterior perspective view of the inlet end plate of the evaporator of FIG. 6.

FIG. 8 is an interior perspective view of the inlet end plate of the evaporator of FIG. 6.

FIG. 9 is a perspective view of a two pass evaporator.

FIG. 10 is a perspective view of the inlet/outlet end plate of the evaporator of FIG. 9.

DETAILED DESCRIPTION OF THE DRAWINGS

The shell and tube evaporator of the present invention is shown generally at 10 in FIG. 1. Evaporator 10 includes a shell 12 enclosing a tube bundle 32. A tube sheet plate view of the evaporator is depicted in FIG. 2.

The shell 12 is comprised of a cylindrical outer shell 14 that is preferably made of a metallic material. The shell 14 is formed of a wall that defines an inner volume 16 in which the tube bundle 32 is disposed and through which a volume of refrigerant flows.

The shell 12 is generally disposed in a horizontal disposition and accordingly, a pair of supports 18 is affixed to the underside of the shell 12 for supporting the evaporator 10 on an underlying surface.

The shell 12 further includes a pair of endplates 20, 22 that seal the cylindrical outer shell 14. Endplate 20 is a refrigerant inlet plate and endplate 22 is a refrigerant outlet plate.

A refrigerant inlet 28 is defined in the endplate 20 and a refrigerant outlet 30 is defined in the endplate 22.

A water inlet 24 is affixed to the cylindrical outer shell 14 and a water outlet 26 is also affixed to the cylindrical outer shell 14 spaced apart from the water inlet 24. Generally, the water inlet 24 and the water outlet 26 are disposed proximate the endplates 20, 22 respectively.

The water inlet 24 is in fluid communication with the tube bundle 32 at a first end thereof The water outlet 26 is in fluid communication with the fluid bundle 32 at a second spaced apart end thereof The tube bundle 32 is made up of a plurality of tubes and baffle plates used for heat transfer enhancement that extend generally the full length of the inner volume 16 of the shell 12. An exemplary tube 34 of the tube bundle 32 is included for clarity. With the baffle plates, water will pass each baffle plate so that the water will have cross flow outside of the tube bundle. The baffle plate will cause the water flow to become turbulent flow.

The refrigerant inlet endplate 20 is shown generally in FIGS. 3-4. Endplate 20 is preferably formed of two joined together cones, a first cone 40 and a second cone 42. The first cone 40 has its origin lying on the longitudinal axis 43 of the evaporator 10. The angle defined between the longitudinal axis 43 and the first cone 40 is generally greater than the angle defined between the longitudinal axis 43 and the second cone 42. It should be noted that the second cone 42 also has its origin lying on the longitudinal axis 43. The second cone 42 is truncated proximate its origin and a flange 45 is provided for coupling to a refrigerant inlet pipe. The refrigerant inlet 28 is defined interior to the flange 45. It is understood that the endplate 20 could be other shapes, which would affect the shapes of the vanes discussed below. For example, the end plated 20 could be formed of a single cone.

Referring to FIGS. 3 and 4, the vanes of the present invention are depicted. In a preferred embodiment, there are five vanes disposed within the endplate 20, a center vane 44, a first vane set 46, and a second vane set 48. Preferably, each of the vanes 44, 46, and 48 is formed of two joined trapezoids in a common plane, a first trapezoid 50 and a second trapezoid 52. Generally, the angled sides of the first trapezoid 50 of each of the vanes 44, 46, and 48 has a lesser included angle than the angled sides of the second trapezoid 52. Generally, the angled sides 51 of the first trapezoid 50 conform with the interior margin of the second cone 42 while the angled sides 53 of the second trapezoid 52 conforms with the interior margin of the first cone 40.

The sides 51, 53 may be formed integral the respective cones 42, 40. A single trapezoid shape would suffice for the vanes 44, 46, and 48 for use with an end plate 20 that is formed of a single cone, as noted above. In any event, the vanes 44, 46, and 48 should be formed such that the side margins of each of the vanes 44, 46, and 48 conform the interior margin of the end plated 20 at the selected angle of disposition of the respective vanes 44, 46, and 48 relative to the centerline 43. This is discussed in greater detail below.

As noted above, in a preferred embodiment, the vanes 44, 46, and 48 are formed integral with the endplate 20. Preferably, such formation is by a casting process.

As depicted in FIGS. 3 and 4, the center vane 44 lies coincident with a generally horizontal plane defined through the longitudinal axis 43. The plane is generally parallel with the underlying surface on which the evaporator 10 is mounted. The first vane set 46 lies at a first angle A relative to the longitudinal axis 43. An upper vane of the first vane set 46 is angled upward at the angle A to deflect incoming refrigerant upward and the second vane of the first vane set 46 is angled downward at the angle A′ to deflect incoming refrigerant downward.

The second vane set 48 is also angled relative to the longitudinal axis 43, but at an angle B, a greater angle than that of the first vane set 46. The upper vane of the second vane set 48 is angled upward at the angle B to deflect refrigerant that is incoming to the top most portion of the evaporator 10. The lower vane of the second vane set 48 is angled downward at the angle B′ to deflect incoming refrigerant to the lower most portion of the evaporator 10. In this manner, the vanes 44, 46, and 48 provide mixture of the incoming refrigerant liquid and vapor and promote even distribution of the incoming refrigerant mixture throughout the evaporator 10.

A second embodiment of the evaporator 10 of the present invention is depicted in FIGS. 5-7. The evaporator 10 of this embodiment acts like two evaporator, in that the evaporator 10 has two independent refrigerant flow paths A and B. A substantially vertical plate 54 (a first end of which is depicted in FIG. 7) in the shell head at the inlet separates the two refrigerant flow so that they do not mix together. The refrigerant in the two portions 16 a, 16 b does not mix in the evaporator 10, but passes thru the evaporator 10 independently.

Effectively then, the evaporator 10 is with two independent refrigerant circuits. Refrigerant flow is as indicated by the arrows. A first refrigerant flow flows in refrigerant inlet 28 a, through the portion 16 a of the evaporator inner volume 16 and out the refrigerant outlet 30 a. A second refrigerant flow flows in refrigerant inlet 28 b, through the portion 16 b of the evaporator inner volume 16 and out the refrigerant outlet 30 b, the plate 54 acting to separate the two refrigerant flows.

The embodiment includes two sets of side-by-side vanes, variously designated by a and b in FIG. 7. Additionally there is a third vane set 56 a and 56 b. As noted above, in a preferred embodiment, the vanes 44 a, 44 b, 46 a, 46 b, 48 a, 48 b, 56 a, and 56 b are formed integral with the endplate 20.

A third embodiment of the evaporator 10 of the present invention is depicted in FIGS. 8 and 9. The evaporator 10 of this embodiment acts like a double pass evaporator, in that the evaporator 10 has two refrigerant flow paths A and B and the refrigerant makes two passes through the evaporator 10. A substantially vertical plate 54 (a first end of which is depicted in FIG. 9) in the shell head at the inlet separates the two refrigerant flow so that they do not mix together.

The refrigerant is a single flow in the two portions 16 a, 16 b and does not mix in the evaporator 10. The refrigerant flow A in portion 16 a is reversed by the endplate 22 (endplate 22 in this embodiment has no refrigerant inlets or outlets) and becomes refrigerant flow B in portion 16 b. Effectively then, the evaporator 10 has two side-by-side refrigerant flow paths. Refrigerant flow is as indicated by the arrows.

The refrigerant flows in refrigerant inlet 28, through the portion 16 a of the evaporator inner volume 16 as depicted by arrow A, is reversed by the end plate 22 (endplate 22 notably has no refrigerant inlet or outlet). The refrigerant flow then flows oppositely as depicted by arrow B through the portion 16 b of the evaporator inner volume 16 and out the refrigerant outlet 30 in the end plate 20, the plate 54, similar to the plate 54 described above, acting to separate the two flows.

The embodiment includes a single set of vanes disposed in a first portion 60 of the endplate 20, as depicted in FIG. 9. Additionally there is a third vane set 56. As noted above, in a preferred embodiment, the vanes 44, 46, 48, and 56 are preferably formed integral with the endplate 20. There are no vanes in the second portion 62 of the end plate 20, the second portion 62 being fluidly coupled to the refrigerant outlet 30.

In operation of the first embodiment of the evaporator 10, water flows in through the water inlet 24 and around the outside surface of the tubes 34 of the tube bundle 32 and of baffle plates, where used. As the water proceeds from the water inlet 24 to the water outlet 26, the water is chilled by refrigerant. The refrigerant enters the refrigerant inlet 28 and is dispersed by the vanes 44, 46, and 48 throughout the evaporator 10. The refrigerant flows through the interior flow channel defined in the respective tubes 34 of the tube bundle 32, cooling the water and simultaneously evaporating the refrigerant. Accordingly, almost all of the refrigerant mixture changes from a liquid state to a vapor state in the evaporator 10 and flows from the evaporator 10 through the refrigerant outlet 30 in the vapor state.

The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims. 

1. An evaporator for use in a refrigeration system, the evaporator having a shell defining an interior volume enclosing a tube bundle comprising a plurality of elongate tubes, a water inlet in fluid communication with a first end of the tube bundle for directing water to the first end of the tube bundle and a water outlet in fluid communication with a second end of the tube bundle for passing water received from the second end of the tube bundle out from the interior volume, comprising: a plurality of fluid deflectors in fluid communication with a first refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout at least a first portion of the interior volume.
 2. The evaporator of claim 1, the fluid deflectors being a plurality of vanes.
 3. The evaporator of claim 2, the vanes being angled at selected angles to deflect the incoming refrigerant both upward and downward relative to an evaporator center line.
 4. The evaporator of claim 2 a first vane being generally planar and being disposed generally on an evaporator centerline in a generally horizontal disposition.
 5. The evaporator of claim 2, a first pair of vanes, each vane of the pair being generally planar and being disposed generally at a first selected angle with respect to an evaporator centerline.
 6. The evaporator of claim 5, a second pair of vanes, each vane of the pair being generally planar and being disposed generally at a second selected angle with respect to an evaporator centerline.
 7. The evaporator of claim 1, the plurality of fluid deflectors being formed integral, unitary with an end plate.
 8. The evaporator of claim 1, the plurality of fluid deflectors being cast integral, unitary with an end plate.
 9. The evaporator of claim 1, each of the plurality of fluid deflectors being formed such that a side margin of each of the fluid deflectors conforms to an interior margin of an end plate at a selected angle of disposition of each of the respective fluid deflectors.
 10. The evaporator of claim 1, each of the plurality of fluid deflectors being formed of at least one planar trapezoidal shape.
 11. The evaporator of claim 1, including a plurality of fluid deflectors in fluid communication with a second refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout a second portion of the interior volume.
 12. The evaporator of claim 1, a first plurality of fluid deflectors being operably coupled to a first portion of an end plate and a second plurality of fluid deflectors being operably coupled to a second portion of the end plate to define two independent refrigerant flows.
 13. The evaporator of claim 1, the plurality of fluid deflectors being operably coupled to a first portion of an end plate and a second portion of the end plate being without fluid deflectors to define two independent refrigerant flows.
 14. A method of forming an evaporator for use in a refrigeration system, the evaporator having a shell defining an interior volume enclosing a tube bundle comprising a plurality of elongate tubes, a water inlet in fluid communication with a first end of the tube bundle for directing water to the first end of the tube bundle and a water outlet in fluid communication with a second end of the tube bundle for passing water received from the second end of the tube bundle out from the interior volume, comprising: selectively disposing a plurality of fluid deflectors in fluid communication with a first refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout at least a portion of the interior volume.
 15. The method of claim 14, including forming the fluid deflectors of a plurality of vanes.
 16. The method of claim 15, including angling the vanes at selected angles to deflect the incoming refrigerant both upward and downward relative to an evaporator center line.
 17. The method of claim 15, including forming a first vane being generally planar and disposing the vane generally on an evaporator centerline in a generally horizontal disposition.
 18. The method of claim 15, including forming a first pair of vanes and forming each vane of the pair planar and disposing each vane of the pair generally at a first selected angle with respect to an evaporator centerline.
 19. The method of claim 18, including forming a second pair of vanes and forming each vane of the pair planar and disposing each vane of the pair generally at a first selected angle with respect to an evaporator centerline.
 20. The method of claim 14, including forming the plurality of fluid deflectors integral, unitary with an end plate.
 21. The method of claim 14, including casting the plurality of fluid deflectors integral, unitary with an end plate.
 22. The method of claim 14, including forming each of the plurality of fluid deflectors such that a side margin of each of the fluid deflectors conforms to an interior margin of an end plate at a selected angle of disposition of each of the respective fluid deflectors.
 23. The method of claim 14, including forming each of the plurality of fluid deflectors of a planar trapezoidal shape.
 24. The method of claim 14, including fluidly communicating a plurality of fluid deflectors with a second refrigerant inlet for promoting mixing of incoming refrigerant in various states and distributing such mixed refrigerant generally evenly throughout a second portion of the interior volume.
 25. The method of claim 14, including operably coupling a first plurality of fluid deflectors being to a first portion of an end plate, operably coupling a second plurality of fluid deflectors to a second portion of the end plate and thereby defining two independent refrigerant flows.
 26. The method of claim 14, including operably coupling a plurality of fluid deflectors to a first portion of an end plate, forming a second portion of the end plate being without fluid deflectors and thereby defining two independent refrigerant flows. 